Where is the biggest clock?

Tehran 24 ran a photo of a huge clock somewhere in Tehran, under the headline of “The World’s Biggest Clock.”

But is it more than 37 feet across, like the flower clock in Las Colinas, Irving, Texas?*

• Photo from Glenn Boyden

What is the biggest clock in the world? Surely there are some bigger.

* This site says the Tehran clock is 15 meters across — bigger than Las Colinas. The clock faces accompanying the bell of Big Ben are 7 meters across. For a panoramic view of the belfry of Big Ben, see the Parliament website.